The present invention relates to a device for transmitting signals between a launching site and a missile by means of a light transmission path. More particularly, this device is intended for a weapon system in which missiles are guided from a launching site or base and in which a transmission path for modulated light, more specifically, a laser beam is produced between the base and the missile during the flight of the latter; modulation of the laser beam constituting control signals transmitted from the launching site to the missile and/or information signals transmitted in the opposite direction.
German Offenlegungsschrift DT No. 2,012,293 discloses a weapon system of this type wherein the transmission path consists of a flexible fiber light line designed to be uncoiled from the missile. The fiber light line is connected to a laser or laser diode, both at the launching base and the missile; control signals to the missile or information signals to the launching site, more specifically, from a camera provided on the missile, being transmitted through modulation of the laser or laser diode in time division multiplex. The advantage of transmitting signals by means of modulated light via a light line over signal transmission in which electrical signals are transmitted via a flexible copper line is primarily that of obtaining a broader band width.
The difficulties involved in producing reasonably priced fiber light lines which are capable of transmitting light over long distances with permissible loss ratios, are already known. Accordingly, the object of the present invention is to obviate this disadvantage and to produce a light transmission path in a weapon system of the above-described type without using a fiber light line and without any physical connection between the missile and the launching base.
According to the invention, this problem is solved by providing a transmission path in the form of a laser beam which is continuously aimed on the missile from the launching base by means of a follow-up device and which is reflected back to the base by the missile.
A transmission path of the type described can be produced over considerably longer distances and with a substantially reduced loss ratio as compared to transmission by means of light lines, while fully retaining the advantage of a broader band width. The information to be transferred from the missile to the base, for example, from a camera, can be effected in time division multiplex through modulation of the light reflected back from the missile. To this end, the missile is preferably equipped with at least one triple mirror reflector with an optical modulator connected in series therewith.
The follow-up device which continuously trains the laser beam on the missile preferably comprises a receiver for the reflected laser beam; this receiver being equipped with an angle discriminator so that the angular deflection of the reflected light beam portion from the median axis of the transmitted laser beam can be detected and used to determine the missile position or to control the laser emitter. This angle discriminator can consist of a prism whose top sides are inclined with respect to the base surface at an angle corresponding generally to the limiting angle of total reflection and which bear photoreceivers to which a differential connection is attached.
At least one crown of triple mirror reflectors comprising a modulator disposed in series therewith is preferably distributed about the axis of the missile to enable the missile to reflect the laser beam impinging thereon essentially independently of its instantaneous flight position. The triple mirror reflectors in the crown or crowns can also be inclined at different angles with respect to the axis so that they can reflect light striking parallel to the axis, at right angles to the axis and at intermediate angles thereto.
The laser emitter employed is preferably a powerful laser having a relatively broad transmission beam. CO.sub.2 lasers are particularly suitable. In order to modulate the signals to be transmitted to the missile, a part of the emitted laser beam can be faded out by means of a beam divider and can be directed via an optical modulator.
Other objects will be in part obvious and in part pointed out more in detail hereinafter.
A better understanding of the invention will be obtained from the following detailed description and the accompanying drawing of an illustrative application of the invention.